1. Field of the Invention
The present invention relates to an element for retaining the front of a boot on an alpine ski.
2. Description of Background and Relevant Information
An element of the above-mentioned type is provided to retain the front of the boot in cooperation with a rear element, and to release the boot in the case of excessive force.
The forces exerted between the boot and the ski have a plurality of force or moment components which can be resolved in relation to axes, one of which is the vertical axis of the leg, and another is the longitudinal axis defined by the foot.
One of the main components is the moment in relation to the vertical axis of the leg. This component induces a torsion in the skier""s leg, which is found at the level of the knee joint.
It has been known for a long time that the intensity of the stresses which a knee can withstand without damage depends on the direction in which the leg is biased in torsion. A knee is more fragile during a bias that drives a foot rotationally inward, i.e., toward the other foot.
Thus, a retaining element is known from the published Patent Applications Nos. FR 1 503 847, FR 1 503 848, FR 1 503 849, whose release threshold is different depending on the direction in which the boot biases it. More recently, the Applications FR 2 722 372, FR 2 722 373, FR 2 722 374 and U.S. Pat. Nos. 5,615,498, 5,639,108, 5,702,119 disclose constructions related to this problem. For these retaining elements, the release threshold is higher on the side where the knee is more resistant, and lower on the side where the knee is less resistant.
Such devices yield satisfactory results insofar as the release thresholds are better adapted to the skier""s morphology.
An object of the invention is to further improve the performances of the front retaining elements in this function of adapting to the skier""s morphology.
Other objects and advantages of the invention will become apparent from the description that follows.
The retaining element according to the invention is provided to releasably retain one of the ends of a boot by means of a laterally movable jaw on either side of a centered position aligned with a longitudinal and vertical median plane of the retaining element, in response to a force having a lateral component oriented in either direction against the resistance of an elastic return mechanism. It includes a compensating mechanism acting on the jaw or its return mechanism so as to further facilitate its opening, the compensating mechanism having two active elements either of which is biased as a function of the side where the jaw moves with respect to the vertical and longitudinal median plane.
The two active elements of the invention are asymmetrical with respect to the longitudinal and vertical median plane, such that the compensating mechanism is more or less active depending on the active element biased as a function of the side on which the jaw moves.